Frequency-range extension switch



Sept. 1% 19293, A. H. @REBE 1,727,641

FREQUENCY RANGE EXTENSION SWITCH Filed Jan. 30, 1926 3 Sheets-Sheet l262 I Z 9.53 @0 j? a INVE TOR 44 4 la -flaw ATTORN Y 4 INVENTOR figATTORNEY Sept. 10, 1929 A. H. GREBE FREQUENCY RANGE EXTENSION SWITCHFiled Jan. 5O, 1926 5 Sheets-Sheet 2 Sept. 10, 1929.

A. H. GREBE FREQUENCY RANGE EXTENSION SWITCH 1926 3 Sheets-Sheet 3 FiledJan. 30

NVENTOR QJQ Patented Sept. 10, 1929.

ALFRED HENRY GREBE, OF HOLLIS, NEW YORK.

FREQUENCY-RANGE EXTENSION SWPITCH.

Application filed January 30, 1926. Serial No. 84,922.

This invention relates to range extension switches and has for itsprincipal object the extension of the range of frequencies over which aradio tuning system is capable of opcrating efficiently.

In carrying out my invention, I provide successive tuning systems madeup of inductances and variable capacities and switches operatedsimultaneously, preferably by a common member, to change the inductancesin all of the circuits when the variable capacities reach their upperlimits and when they reach their lower limits of capacity.

In the manufacture of radio tuning systems for receiving broadcastingstations, it has been found impractical to construct eflicientcombinations of an inductance and variable capacity that can besatisfactorily tuned to all frequencies used in broadcasting and Itherefore provide two values of inductance,

one value of inductance being such as to make the receiver tunable to afrequency which is as high or higher than the frequency of anybroadcasting station and the other inductance value being such as tomake the receiver tunable to a frequency which is as low or lower thanthat of any broadcasting station.

The two frequency ranges thus provided may overlap more or less and givea total range from above to below the frequencies at present usedbybroadcasting stations. I also provide an arrangement whereby one controlknob simultaneously varies the frequencies of all of the circuits andautomatically switches to the lower values of inductance when thecondensers, connected to the higher values of inductance, are variedbeyond the point of their minimum capacity and vice versa, switches tothe higher inductance values when the condensers, connected to the lowervalue of inductance, are varied beyond the point of-maximum capacity.

I thus provide an extension of receiving range covering the entirebroadcasting range, and means for automatically and convenientlychanging from either one to the other of the overlapping ranges.

My invention is described and explained ir further detail in connectionwith the follow ing illustrations:

Fig. 1 is a diagrammatic sketch of the circuits and switches of areceiving set.

Fig. 2 is a cross sectional view of a receiving set illustrated in Figs.3 and 4, showing the main control dial switch operating lever, commonbar of the control member and supporting members.

Fig. 3 is a rear view of the set, showing control members, switches,condensers and inductance coils.

Fig. 4 is an enlarged sectional view of a portion of the common movablemember carrying the switch contacts; and

Fig. 5 is a top 'view of the set, showing the control members, switches,inductance coils and circuit connections operated by the switches.

Referring now to the drawings, I have shown in Fig. 1, an arrangement ofinductances and capacities as used in one form of a radio broadcastreceiver wherein I provide for the use of two values of inductance inthe antenna to ground circuit and two values of inductance in each of'three tunable circuits, comprising an inductance and variable capacity.Three inductances 8, each comprising two coils 80, 81 connected inseries with. condensers 9, are so varied by my switching system,hereinafter described in detail, that twqi ranges of radio frequenciesmay be covso ere A bar 20 of insulating material, carries five switchblades 1,12,17 and is movable from left to right in the arrangementshown in this figure. When moved to the left posi- 85 tion. blades 1connect with contacts 2 3 and blade 12 connects with contacts 11, 13.When moved to the right hand position blade 17 connects with contacts16, 18.

In the left position antenna lead 10 connects through contact 11, blade12, contact 13, lead 130, coil 81 at 14 and thence to ground G. Also inthis left position, portions of inductances 8, are short circuitedbetween points 5 and 7 through the switch blades 1, by way of contacts2, 3 and connecting leads 4, 5. In the right hand position a greateramount of inductance is operable in all circuits as the antenna lead 10,is connected 9 through contact 18, switch blade 17 contact 16, lead 160and connection 15 through more turns of coil 81 to ground G; andinductances 8 are not short circuited in any position.

Dial 26, attached to shaft 23 of one of the variable condensers 9, turnswith the variation of the condenser so that a rib 25, on dial 26,presses against a boss 24 when condenser 9 is at minimum capacity and arib 27 presses against boss 24 when condenser 9 is at maximum capacity.

When the minimum range has been reached with all of the inductances orwhen the maximum range has been reached with the lesser inductances dial26 is movable beyond the point of minimum capacity and rib or 27 canpush against boss 24 causing arm 22 to turn about shaft 23 and transferthe motion through pin 21 to bar 20 and thereby move the switch bladesfrom left to right or vice versa, automatically shifting from one set ofinductance values to the other.

Fig. 2 shows in more detail a base 950, front panel 951, dial shields952, 953, variable condenser frames 900, 901, 903, movable plates 91 andfixed plates 92, of a condenser, condenser shaft 23, shaft enlargement232, washer 231, boss 24, arm 22, ribs 25 and 27, dial 26, bar 20, pin21, contacts 2 and 3 and supporting frame 200 for bar 20, together withattached flanged wheels 260 and 262,

and coils 81 and 80 comprising inductance 8.

Fig. 3 shows a rear view of the complete receiver, in which threesimilar tuning condensers are so coupled together by belts that allvariations of the middle condenser, for example, are duplicated in theadjoining condensers.

Beaded belts 264 and 265, extending around and secured to flanged wheels261, 262, 260 and 263, operatively connect the condensers so that themovement of the dial'of any one condenser will produce a similarmovement of the other two dials.

Thumb nuts 270, 271, clamp the flanged wheels 261, and 263 against thedials and when one or the other is unscrewed slightly, it allows thatwheel to slip, without transmitting motion to the condenser, when an-'other dial is turned. Thus, it will be seen, that the dials may beturned separately, in pairs or all three simultaneously. If the slackprovided in the belts 264 and 265 is not sufficient to allow thecondenser to be set with slight differences in capacities to make up forcapacity variation due to the effect of the antenna or metal frameworkin the vicinity, the clamp nuts 270 and 271 may be used to extend theadjustment.

The details of the construction and operation of the unit control meansfor radio receiving sets, above briefly described, will be found fullydisclosed and claimed in my apbered 30,033, now Patent No. 1,608,734,dated November 30, 1926.

Supporting frame 200 is shown fastened by brackets 201 and 202 to thepanel 951.

The details of the frame 200, bar 20, switch blades 1, contacts 2, pin21 and arm 22, are shown in Fig. 4.

Fig. 5 shows a top view of the parts including the belts 264, 265,flanged wheels 261, 262, 263, ribs 25, 27, arm 22, pivot point 23,clearance hole 211 in bar 20 for pin 21, clearance slot 210 in support200, brackets 201,202, slotted spring switch blades 1, 12, 17, andslotted spring contacts 2, 3, 1., 13, 16, 18 together with antennabinding post A, ground G and other numbered parts corresponding to thesimilarly numberedqoarts described in the other figures.

Referring to all figures, the operation is as follows:

When control dial 26, on the shaft 23 of a variable condenser, is movedbeyond the minimum capacity point of the condenser, it presses rib 25against boss 24, causing arm 22 to pivot about 23 and push bar 20 withwhich it is connected through pin 21, so that switch blades 1 and 12connect with contacts 2 and 3 and 11 and 13, thereby reducing the numberof effective turns of wire in the coils and 81. Likewise when dial 26 istuned beyond the maximum capacity of the condenser, rib 27 pressesagainst boss 24 and moves bar 20, so that switch blade 17 is broughtinto contact with 16 and 18 and switch blades 1 and 12' are disconnectedso that the effective number of turns is increased.

The many important advantages of the invention will be apparent from theforegoing description.

Having, therefore, described my invention, what I claim is:

1. Tuning apparatus comprising a plurality of independent inductanceunits, condensers normally rotatable through only 180 connected in shuntwith each of said inductance units providing circuits responsive to apredetermined frequency range said inductances being tapped at aplurality of points along the length thereof, switch contacts connectedwith the taps on said inductances, an actuator, a plurality of switchblades carried by sald actuator and arranged to cooperate with saidcontacts, rotary means for simultancusly varying the capacity of each ofsaid condensers, and a lost motion connection between said rotary meansand said actuator forshifting said actuator to a selected one of eitherof two positions and connecting or disconnecting said switch blades withrespect to said contacts.

2. Tuning apparatus comprising a plurality of independent tuningcircuits, each of said circuits including inductance and variplicationfiled May 13, 1925, and serially numable condenser normally rotatablethrough tacts when said actuating member is moved to a selectedposition, a rotary control device for simultaneously varying thecapacity of each of said condensers, and a lost motion connectionbetween said rotary control device and said actuating member forshifting said actuating member to either of two limiting positions andconnecting or disconnecting said switch blades with selected sets ofcontacts for rendering effective or ineffective selected portions ofsaid inductances in proportion to the adjustment of said condensers.

'3. Tuning apparatus comprising a plurality of tuning circuits eachincluding induc- Y tance and capacity elements connected in series, saidcapacity elements being normally rotatable through only 180 of motion,an actuator for simultaneously controlling the adjustment of saidcapacity elements, said inductance elements being tapped atpredetermined points and connected to sets of switch contacts, switchblades for establishing connection with said contacts, anindependentactuator for controlling the movement of said switch bladesand a lost motion connection between said first mentioned actuatorand-said last mentioned actuator for shifting said last mentionedactuator to either of two limiting positions when said capacity elementsare shifted to maximum or minimum positions.

4. Tuning apparatus comprising a plurality of independent circuits eachincluding inductance and capacity elements connected in series, saidcapacity elements being variable condensers normally rotatable throughonly 180, -taps extending from predetermined points on said inductanceelements to sets of contacts, switch blades cooperating with each ofsaid sets of contacts, a rotary actuator for simultaneously adjustingsaid capacity elements, a control member connected with saidswitch'blades, means extending between said control member and saidrotary actuator for imparting movement to said control, member when saidrotary actuator is moved to either of two limiting positions, wherebysaid switch blades may be shifted with respect to said contacts.

5. Tuning apparatus comprising a plural- I ity of independent tuningcircuits each in eluding inductance and capacity elements, said capacityelements being variable condensers normally rotatable through only 180,and said inductance elements being tapped and having connectionsextending to sets of contacts, switch blades arranged to bridge saidsetsof contacts, a control member carrying said switch blades, a rotaryactuator for simultaneously adjusting said capacity elements betweenmaximum and minimum capacity values, means extending between saidcontrol member and said rotary actuator for shift-ing said controlmember to either of two selected positions when said capacity elementsapproach maximum or minimum values whereby selected ones of said switchblades connect with sets of contacts for shunting portions of saidinductance elements when said rotary actuator is shifted to a positionof minimum capacity value. 1

6. Tuning apparatus comprising a plurality of independent inductances, avariable condenser normally rotatable through only 180 arranged incircuit with each of said inductances, an actuator for simultaneouslycontrolling all of said variable condensers, a switch member connectedwith each of said inductances, a reciprocating member arranged tocontrol each of said switch members and a lost motion connection betweensaid actuator and said reciprocatory member for imparting movement tosaid reciprocatory member at the limits of travel of said actuator.

7.- Tuning apparatus including aplurality of independent tuning circuitseach constituted by inductanceand capacity elements, said capacityelements being normally rotatable through only 180 and variable betweenmax-' member, switch blades carried by said reciprocatory member incooperative relation to said switch contacts, means for shifting saidmember when said variable capacity elements are moved to the maximum andminimum limits for connecting or disconnecting said switch blades fromsaid contacts.

8. Tuning apparatus comprising a plurality of tuning circuits eachincluding inductance and capacity elements, said capacity elements beingnormally rotatable through only 180, a pair of independent actuators,one of said actuators carrying a plurality of switch blades and theother of said actuators connected ,with each of said capacity elementsfor simultaneously varying the capacity thereof between maximum'andminimum limits, contacts connected to taps on portions of saidinductance elements, selected ones of said contacts being connected bysaid switch blades when the actuator carrying said blades is shifted toeither one of two limiting positions, andmeans connecting said actuatorsfor effecting a shift in the position of said switch blades when saidcapacity elements are adjusted to positions of maximum and minimumlimits.

9; Circuittuningmeanscomprisinganinductance variable to two values, avariable capacity normally rotatable through only 180,

and means for automatically varying the inductance when the capacityreaches minimum and maximum values so as to render the variable capacityeffective throughout its entire range with each value of the inductance.

10. Circuit tuning means comprising an inductance variable to twovalues, and a variable capacity normally rotatable through only 180", aswitch for varying the inductance, a control member for varying the capacity, and a connection between the switch and capacity control member,which operates to change the value of the inductance only at theminimumand maximum capacity positions of the control member, whereby thevariable capacity is rendered effective throughout its entire range witheither value of the inductance.

11. In a radio receiver, tuning means comprising an inductance in serieswith a variable condenser normally rotatable through only 180, means forgiving the inductance either of two values, and means operated from thevariable condenser to control the first said means so as to change theinductance to its higher value at the maximum adjustment of thecondenser and to change the inductanceto its lower value at the minimumadjustment of the condenser.

ALFRED HENRY GREBE.

